title: Immobilization-induced increase in fatigue resistance is not explained by changes in the muscle metaboreflex.
abstract: Immobilization has been reported to enhance fatigability, which is paradoxical in light of the metabolic and molecular alterations that occur in atrophied muscles. We examined whether the immobilization-induced enhancement in fatigability was associated with attenuation in the muscle metaboreflex response. Ten subjects were examined after 3 weeks of hand-forearm immobilization. The time to task failure of a handgrip contraction (20% intensity) was determined along with heart rate (HR) and mean arterial pressure (MAP) at rest, during the task and during a 2-min postexercise muscle ischemia (PEMI) test that continues to stimulate the metaboreflex. Immobilization decreased strength by 25% (P<0.01) and increased the time to task failure by 21% (P=0.03). However, no changes were observed for the HR and MAP responses to the exercise task or during PEMI (P>0.05). These findings indicate that the augmentation of time to task failure with immobilization is not associated with changes in the pressor or metaboreflex responses.
authors.affiliation: Institute for Neuromusculoskeletal Research, Department of Biomedical Sciences, 211 Irvine Hall, Ohio University, Athens, Ohio 45701, USA.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Clark
authors.affiliation: Institute for Neuromusculoskeletal Research, Department of Biomedical Sciences, 211 Irvine Hall, Ohio University, Athens, Ohio 45701, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hoffman
authors.affiliation: School of Physical Therapy, Ohio University, Athens, Ohio, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Russ
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D015444:Exercise / Q000502:physiology; D005221:Fatigue / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007103:Immobilization / Q000379:methods*; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000503:physiopathology*; D013997:Time Factors; D055815:Young Adult